Light emitting device for emitting diffuse ultraviolet light

ABSTRACT

A diffusive layer including a laminate of a plurality of transparent films is provided. At least one of the plurality of transparent films includes a plurality of diffusive elements with a concentration that is less than a percolation threshold. The plurality of diffusive elements are optical elements that diffuse light that is impinging on such element. The plurality of diffusive elements can be diffusively reflective, diffusively transmitting or combination of both. The plurality of diffusive elements can include fibers, grains, domains, and/or the like. The at least one film can also include a powder material for improving the diffusive emission of radiation and a plurality of particles that are fluorescent when exposed to radiation.

REFERENCE TO RELATED APPLICATIONS

The current application is a continuation-in-part application of U.S.patent application Ser. No. 15/444,799, filed on 28 Feb. 2017, whichclaims the benefit of U.S. Provisional Application No. 62/301,015, filedon 29 Feb. 2016, each of which is hereby incorporated by reference.Aspects of the invention described herein are related to U.S. patentapplication Ser. No. 14/478,266, filed on 5 Sep. 2014, which is herebyincorporated by reference.

TECHNICAL FIELD

The disclosure relates generally to emitting devices, and moreparticularly, to a diffusive layer for an emitting device in order toimprove diffusive light emission.

BACKGROUND ART

When using discrete light sources, such as light emitting diodes, tocreate an illumination effect, there is a need for blending theillumination created by these discrete light sources into a uniformlighting condition. For example, a linear array of discrete lightsources will produce non-uniform emission which can be very detrimentalfor sterilization purposes.

Light guides made from a high refractive index material have beensuccessfully employed to create a line of light from a point source. Forexample, one approach discloses an optical element that uses atotal-internal reflection light guide to create a line of light from oneor two light emitting diode point sources by internally reflecting thelight along an axis, wherein beams of light escape the light pipe alongthe axis of the pipe. This form of lighting apparatus is designed suchthat the light guide is to be hidden inside a wall or panel. Inaddition, the length of the light line created is limited by theconstraints on the length of the mold used to create the light guides.Other approaches also use total internal reflection to create a line oflight from a point source. While these approaches achieve a sufficientlythin line of light, the length of the line is effectively limited andthe light guides cannot be easily configured end-to-end to create alonger continuous line of light. Furthermore, these approaches use avery limited number of light sources, which in turn restricts theluminance and perceived visual brightness of the resulting line. Theapproaches use light guides to direct a point source of light into aline of light, so each approach is limited on luminance. As such, a lineof light with high luminance and sufficient length cannot be achieved.An additional drawback is the fact that only a single pattern isachievable with this type of display. Furthermore, for ultraviolet lightemitting devices, long light guiding layers are expensive.

SUMMARY OF THE INVENTION

Aspects of the invention provide a diffusive layer including a laminateof a plurality of transparent films. At least one of the plurality oftransparent films includes a plurality of diffusive elements with aconcentration that is less than a percolation threshold. The pluralityof diffusive elements are optical elements that diffuse light that isimpinging on such element. The plurality of diffusive elements can bediffusively reflective, diffusively transmitting or combination of both.The plurality of diffusive elements can include fibers, grains, domains,and/or the like. The at least one film can also include a powdermaterial for improving diffusive emission of radiation and a pluralityof particles that are fluorescent when exposed to the radiation.

A first aspect of the invention provides a device, comprising: a set ofradiation sources configured to emit radiation; and a diffusive layerlocated adjacent to the set of radiation sources, the diffusive layerincluding a plurality of transparent films, wherein at least one of thetransparent films includes a plurality of diffusive elements, andwherein a concentration of the plurality of diffusive elements is belowa percolation threshold.

A second aspect of the invention provides a device, comprising: a set ofradiation sources configured to emit radiation; and a diffusive layerlocated adjacent to the set of radiation sources, the diffusive layerincluding a plurality of transparent films, wherein at least one of thetransparent films is formed of a fluoropolymer and at least one of thetransparent films is formed of a fluoropolymer composite materialincluding a fluoropolymer and a plurality of diffusive elements, andwherein a concentration of the plurality of diffusive elements is belowa percolation threshold.

A third aspect of the invention provides an enclosure, comprising: aplurality of radiation sources configured to emit radiation; a pluralityof mirror elements, wherein each radiation source is located above amirror element; and a diffusive layer located on a side of the enclosureopposite of the plurality of radiation sources, the diffusive layerincluding a plurality of transparent films, wherein at least one of thetransparent films includes a plurality of diffusive elements, andwherein a concentration of the plurality of diffusive elements is belowa percolation threshold.

The illustrative aspects of the invention are designed to solve one ormore of the problems herein described and/or one or more other problemsnot discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various aspects of the invention.

FIG. 1 shows an illustrative diffusive layer according to an embodiment.

FIG. 2 shows an illustrative diffusive layer according to an embodiment.

FIG. 3 shows an illustrative diffusive layer according to an embodiment.

FIG. 4 shows an illustrative diffusive layer according to an embodiment.

FIGS. 5A and 5B show illustrative system according to embodiments.

FIG. 6 shows an illustrative device according to an embodiment.

FIG. 7 shows an illustrative system according to an embodiment.

FIG. 8 shows an illustrative intensity plot according to an embodiment.

FIG. 9A shows an illustrative device according to an embodiment, whileFIG. 9B shows an illustrative system according to an embodiment.

FIG. 10 shows an illustrative system according to an embodiment.

FIGS. 11A and 11B show radiation intensity and microorganism activityplots over time for an illustrative system according to an embodiment.

It is noted that the drawings may not be to scale. The drawings areintended to depict only typical aspects of the invention, and thereforeshould not be considered as limiting the scope of the invention. In thedrawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, aspects of the invention provide a diffusive layerincluding a laminate of a plurality of transparent films. At least oneof the plurality of transparent films includes a plurality of diffusiveelements with a concentration that is less than a percolation threshold.The plurality of diffusive elements are optical elements that diffuselight that is impinging on such element. The plurality of diffusiveelements can be diffusively reflective, diffusively transmitting orcombination of both. The plurality of diffusive elements can includefibers, grains, domains, and/or the like. The at least one film can alsoinclude a powder material for improving diffusive emission of radiationand a plurality of particles that are fluorescent when exposed to theradiation.

As used herein, unless otherwise noted, the term “set” means one or more(i.e., at least one) and the phrase “any solution” means any now knownor later developed solution. Furthermore, as used herein, ultravioletradiation/light means electromagnetic radiation having a wavelengthranging from approximately 10 nanometers (nm) to approximately 400 nm,while ultraviolet-C (UV-C) means electromagnetic radiation having awavelength ranging from approximately 100 nm to approximately 280 nm,ultraviolet-B (UV-B) means electromagnetic radiation having a wavelengthranging from approximately 280 to approximately 315 nanometers, andultraviolet-A (UV-A) means electromagnetic radiation having a wavelengthranging from approximately 315 to approximately 400 nanometers.

It is understood that, unless otherwise specified, each value isapproximate and each range of values included herein is inclusive of theend values defining the range. As used herein, unless otherwise noted,the term “approximately” is inclusive of values within +/− ten percentof the stated value, while the term “substantially” is inclusive ofvalues within +/− five percent of the stated value. Unless otherwisestated, two values are “similar” when the smaller value is within +/−twenty-five percent of the larger value. A value, y, is on the order ofa stated value, x, when the value y satisfies the formula 0.1x≤y≤10x. Asused herein, a “characteristic size” of an object corresponds to ameasurement of the physical size of the object that defines itsinfluence on a system.

As also used herein, a layer is a transparent layer when the layerallows at least ten percent of radiation having a target wavelength,which is radiated at a normal incidence to an interface of the layer, topass there through. Furthermore, as used herein, a layer is a reflectivelayer when the layer reflects at least ten percent of radiation having atarget wavelength, which is radiated at a normal incidence to aninterface of the layer. In an embodiment, the target wavelength of theradiation corresponds to a wavelength of radiation emitted or sensed(e.g., peak wavelength+/− five nanometers) by an active region of anoptoelectronic device during operation of the device. For a given layer,the wavelength can be measured in a material of consideration and candepend on a refractive index of the material.

Turning to the drawings, FIG. 1 shows an illustrative diffusive layer 10according to an embodiment. The diffusive layer 10 can be used todiffusively reflect radiation emitted from a set of light emittingdiodes (not shown) located adjacent to the diffusive layer 10. In anillustrative embodiment, the diffusively reflected ultraviolet radiationcan be used to disinfect a set of articles. In an embodiment, thediffusive layer 10 can be used to diffusively reflect radiation fromother emitters, such as a high intensity ultraviolet lamp (e.g., a highintensity mercury lamp), a discharge lamp, super luminescent LEDs, laserdiodes, and/or the like. The set of light emitting diodes can bemanufactured with one or more layers of materials selected from thegroup-III nitride material system (e.g., Al_(x)In_(y)Ga_(1-x-y) N, where0≤x, y≤1, and x+y≤1 and/or alloys thereof).

The diffusive layer 10 comprises a transparent film 12 or a plurality oftransparent films 12 with at least one film including a plurality ofdiffusive reflective or transmitting elements 14. In an embodiment, theplurality of transparent films 12, and therefore the diffusive layer 10,can have a transparency of at least 30% to radiation directedperpendicular to the surface of the plurality of transparent films 12.The plurality of transparent films 12 can be merged together though anyprocess. For example, the plurality of transparent films 12 can bemerged together using a melting process, which can include, but is notlimited to placing the plurality of transparent films 12 in an oven andheating the plurality of transparent films 12 to a temperature thatleads to the plurality of films melting. In another embodiment, thediffusive layer 10 can comprise an alloy or mixture of severalfluoropolymer films. Each of the plurality of transparent films 12 cancomprise a fluoropolymer, such as Teflon®, fluorinatedethylene-propylene (EFEP), ethylene-tetrafluoroethylene (ETFE), and/orthe like. In an embodiment, more than one polymer material can be usedto fabricate the diffusive layer 10.

In an embodiment, at least one transparent film in the plurality oftransparent films 12 includes a plurality of diffusively reflecting ortransmitting elements 14. In an embodiment, the plurality of diffusivelyreflecting or transmitting elements 14 can be immersed within the atleast one transparent film. It is understood that the plurality ofdiffusively reflecting or transmitting elements 14 can be located in anyportion of the at least one transparent film (e.g., on the surface ofthe at least one film, partially embedded within a top or bottom surfaceof the at least one film, or completely embedded within the at least onefilm). In an embodiment, at least one film in the plurality oftransparent films 12 is a light guiding layer. The plurality ofreflecting elements 14 can comprise grains, domains, fibers, elongatedfibers, spheres, and/or the like. In an embodiment, the plurality ofdiffusively reflecting or transmitting elements 14 can be formed offibers that form a periodic structure. In an embodiment, a concentration(e.g., density) of the plurality of diffusively reflecting ortransmitting elements 14 is below a percolation threshold. This is toensure that the plurality of diffusively reflecting elements 14 do notform a large cluster of physically touching elements. In an embodiment,small clusters of physically touching elements 14 can be formed. Acharacteristic size (e.g., diameter) of each small cluster is at most 5%of the characteristic size of the plurality of the diffusivelyreflecting or transmitting elements 14. The plurality of diffusivelyreflecting elements 14 can be in an ordered or random arrangement. In anembodiment, the concentration of the plurality of diffusively reflectingelements 14 can be periodically spatially modulated, with the modulationperiod comparable to or larger than the peak wavelength of the emittedradiation from the set of light emitting diodes (not shown). In anembodiment, the plurality of diffusively reflecting elements 14 comprisefibers and the distance between the fibers is on the order of the peakwavelength of the emitted radiation.

The plurality of diffusively reflecting elements 14 can comprise anyshape, such as spheres, cubes, rectangles, triangles, and/or the like.For example, in FIG. 1, the plurality of diffusively reflecting elements14 are sphere shaped. The plurality of diffusively reflecting elements14 can be formed of silicon dioxide (SiO₂), aluminum oxide (Al₂O₃),magnesium fluoride (MgF₂), calcium fluoride (CaF₂), zinc oxide (ZnO),aluminum zinc oxide (AlZnO), and/or the like, with a characteristic sizethat is larger than or comparable to the peak wavelength of the emittedradiation from the set of light emitting diodes (not shown), wherecomparable means the deviation from the peak wavelength by less than anorder of magnitude. In an embodiment, the characteristic size of theplurality of diffusively reflecting elements 14 is larger by an order ofmagnitude than the peak wavelength of the emitted radiation and the atleast one transparent film including the plurality of diffusivelyreflecting elements 14 can include a powder material immersed within theat least one film. In an embodiment, the powder material acts asdiffusive reflective or transmitting centers. The powder material cancomprise SiO₂, Al₂O₃, MgF₂, CaF₂, aluminum, polytetrafluoroethylene(PTFE), a highly ultraviolet reflective expanded polytetrafluoroethylene(ePTFE) membrane (e.g., GORE® Diffuse Reflector Material), and/or thelike. In an embodiment, the distribution of the powder material and theplurality of diffusively reflecting elements 14 is selected along withthe position of the set of light emitting diodes (not shown) to achievea distribution of intensity of radiation that varies throughout thesurface of the diffusive layer 10 by no more than 50%.

In an embodiment, several of the films in the plurality of transparentfilms 12 can include a plurality diffusively reflecting elements 14. Inan embodiment, each film can include a specific type of element 14(e.g., fibers, grains, domains, and/or the like) with a specificmaterial type, a specific characteristic size, a specific shape, and aspecific arrangement with a characteristic separation distance. Forexample, a first film in the plurality of transparent films 12 caninclude a plurality of SiO₂ spheres, while a second film can include aplurality of prolonged aluminum reflective filaments (e.g., fibers).

It is understood that fluoropolymer films are only illustrative ofvarious transparent materials that may be utilized. In anotherembodiment, one or more of the transparent films 12 can be formed ofanother transparent material. For example, one or more of thetransparent films 12 can be formed of silicone. In still anotherembodiment, one or more of the transparent films 12 can comprise acomposite of silicone with a plurality of diffusively reflecting ortransmitting elements 14 as described herein. For example, one or moreof the transparent films 12 can be formed of a silicone film and Alpowder, SiO₂ nanoparticles, and/or the like.

Turning now to FIG. 2, an illustrative diffusive layer 20 according toan embodiment is shown. The diffusive layer 20 can include a pluralityof transparent films 22A, 22B. The first film 22A can include a firstplurality of diffusively reflecting elements 24A located on a first sideand a second plurality of diffusively reflecting elements 24B located ona second side. It is understood that the first plurality of diffusivelyreflecting elements 24A and the second plurality of diffusivelyreflecting elements 24B can be the same or different. For example, afilm in the plurality of transparent films 22A can include a pluralityof SiO₂ spheres 24A on a first side and a plurality of SiO₂ spheres 24Bon a second side. It is understood that although the plurality ofspheres 24A, 24B are shown in the surface of the first film 22A and thesecond film 22B, as mentioned herein, the plurality of spheres 24A, 24Bcan be partially or completely embedded within both or either one of thefirst and second films 22A, 22B. Although the first plurality ofdiffusively reflecting elements 24A are shown as aligned with the secondplurality of diffusively reflecting elements 24B, it is understood thatthe relative position of the plurality of diffusively reflectingelements 24A, 24B can be shifted to be not aligned with one another.

Turning now to FIG. 3, an illustrative diffusive layer 30 according toan embodiment is shown. The diffusive layer 30 can include a transparentfilm 32 in the plurality of transparent films including multiple typesof a plurality of elements 34A-D. Each of the plurality of elements34A-D can be a different type of element. For example, the transparentfilm 32 can include a plurality of diffusive spheres 34A in parallelwith a plurality of diffusive spheres 34B. The plurality of diffusivespheres 34A, 34B can be reflective and/or transmitting. The transparentfilm 32 can also include a plurality of partially reflective, partiallytransparent domains 34C. In an embodiment, the plurality of partiallyreflective, partially transparent domains 34C can comprise, for example,a fluoropolymer, such as polytetrafluoroethylene (PTFE) (e.g., Teflon®),silicone, and/or the like, film of varying thickness. The variation ofthickness is such that the film transparency is maintained in regionstransparent to UV radiation. In an embodiment, the transparency of thefilm is at least 30%. The reflective regions of the film can be of anydesirable thickness, but should generally be on the same order ofmagnitude as the thickness of the transparent regions. The transparentfilm 32 can also include a plurality of domains 34D with variablereflective properties due to variation in the density of the aluminumreflective particles (e.g., aluminum powder) within each domain 34D.

Regardless, it is understood that for each plurality of elements 34A-D,the same or different materials can be used simultaneously. For example,SiO₂ can be used for one of the plurality of elements 34A-D, while Al₂O₃can be used for another of the plurality of elements 34A-D. Furthermore,it is understood that the plurality of elements 34A-D can have the sameor different shapes. For example, one of the plurality of elements 34A-Dcan comprise spheres, while the other of the plurality of elements 34A-Dcan comprise fibers. In addition, the transparent film 32, and any ofthe other embodiments of the diffusive layer discussed herein, caninclude a plurality of particles that are fluorescent under ultravioletradiation in order to provide a visual indication of the ultravioletradiation status and homogeneity. The fluorescent particles can includephosphorus, such as Ca₅(PO₄)₃(F,Cl):Sb³⁺,Mn²⁺, and/or the like. In anembodiment, the concentration of the plurality of particles that arefluorescent under ultraviolet radiation can vary proportionally with theconcentration of the plurality of elements 34A-D.

Turning now to FIG. 4, an illustrative diffusive layer 40 according toan embodiment is shown. The diffusive layer 40 includes a plurality oftransparent films 42, where at least one transparent film has aplurality of diffusive elements 44, as discussed herein with respect tothe other embodiments. Although only one plurality of diffusive elements44 are shown in the diffusive layer 40, it is understood that thediffusive layer 40 can include any number of plurality of diffusiveelements 44, similar to the embodiment of the diffusive layer 30 shownin FIG. 3. In addition, the diffusive layer 40 can include a pluralityof wave guiding structures 46. The plurality of wave guiding structures46 can comprise an ultraviolet (UV) transparent material, such as SiO₂,Al₂O₃, and/or the like. The characteristic width of each of theplurality of wave guiding structures 46 is measurable in microns. Forexample, the width of each of the plurality of wave guiding structures46 is approximately a few microns (e.g., 1-10 microns). Similar tooptical fiber, each of the plurality of wave guiding structures 46 cancomprise a core and a cladding layer (not shown). In an embodiment, thecore layer and the cladding layer can be formed of different materials.The core layer can be formed of, for example, Al₂O₃, while the claddinglayer is formed of, for example, SiO₂. In another example, the claddinglayer can be MgF₂ and CaF₂. In an embodiment, the plurality of waveguiding structures 46 do not comprise optical fibers and can be largerlight guiding structures that are capable of supporting a large numberof light guiding modes. In operation, a set of light emitting diodes(not shown) can be positioned to direct and focus the radiation withinthese light guiding layers. The light guiding structures can be coupled(e.g., directly linked or within close proximity) to a film 42 includingthe plurality of diffusive elements 44.

Turning now to FIGS. 5A-5B, illustrative devices 50A, 50B including afirst diffusive layer 100A and a second diffusive layer 100B accordingto embodiments are shown. The first and second diffusive layers 100A,100B can comprise any combination of features of diffusive layersdescribed herein, such as the diffusive layers 10, 20, 30, 40 shown inFIGS. 1-4. The first and second diffusive layers 100A, 100B can beconfigured substantially identically, as shown in FIG. 5A, or the firstand second diffusive layers 100A, 100B can be configured differently, asshown in FIG. 5B.

As shown in FIG. 5B, the device 50B can include a set of light emittingdiodes 52A, 52B that are positioned adjacent to the diffusive layers100A, 100B of the device 50B. For example, the set of light emittingdiodes 52A, 52B can be positioned at the sides of the device 50B. In anembodiment, the set of light emitting diodes 52A, 52B can includeoptical reflectors 54 and/or optical lenses 56 to create the angulardistribution of radiation 58 which allows for a uniform distribution ofintensity over and through the diffusive layer 100B. In the embodimentshown in FIG. 5B, the first diffusive layer 100A is reflective and cancomprise a composite material with reflective properties. For example,the diffusive layer 100A can include a PTFE fluoropolymer film with aplurality of aluminum fibers. Alternatively, the diffusive layer 100Acan include a highly ultraviolet reflective expandedpolytetrafluoroethylene (ePTFE) membrane (e.g., GORE® Diffuse ReflectorMaterial), and/or the like. The second diffusive layer 100B istransparent and comprise at least one transparent film with a pluralityof diffusive elements, as discussed herein.

Turning now to FIG. 6, an illustrative device 60 according to anembodiment is shown. The device 60 includes a plurality of UV sources62A-C that are each located a distance h1, h2, h3 above a respectivemirror element 64A-C having a diameter D1-D3 within an enclosure 66.Further details of this device 60 are described in U.S. patentapplication Ser. No. 14/478,266. The mirror elements 64A-C areconfigured to scatter the radiation emitted from the UV sources 62A-Cthroughout the enclosure 66. As shown, the device 60 can include adiffusive layer 200 through which the scattered radiation exits theenclosure 66. The diffusive layer 200 can comprise any combination offeatures of diffusive layers described herein, such as one of theembodiments of the diffusive layers 10, 20, 30, 40 described in FIGS.1-4. The position and size of the mirror elements 64A-C are selected toimprove a uniformity of the radiation exiting the enclosure 66. In anembodiment, the mirror elements 64A-C can be partially transparent to UVradiation in order to improve the uniformity of the radiation beneaththe mirror elements 64A-C.

Turning now to FIG. 7, an illustrative system 300 according to anembodiment is shown. The system 300 can include a plurality of conveyorbelts 310A-C, which are used to move a set of items 302 from oneconveyor belt 310A-C to another in order to disinfect the set of items302. During movement of the set of items 302 from a first conveyor belt310A to a second conveyor belt 310B, it is understood that the set ofitems 302 may rotate 306 in order to improve disinfection of all thesurfaces of the set of items 302. Each of the plurality of conveyorbelts 310A-C can comprise any combination of features of diffusivelayers described herein, such as one of the diffusive layers 10, 20, 30,40 discussed in FIGS. 1-4. In an embodiment, at least one set ofultraviolet radiation sources 304A-D can be located within the conveyorbelts 310A-C. A set of ultraviolet radiation sources 304E can also belocated above the conveyor belt 310A. It is understood that a set ofultraviolet radiation sources can be located above the other conveyorbelts 310B, 310C.

Turning now to FIG. 8, an illustrative intensity plot 400 for a deviceincluding at least one diffusive layer according to an embodiment isshown. A device, such as any of the devices 50A, 50B, 60 shown in FIGS.5A, 5B, and 6 or a system 300 shown in FIG. 7, can include a pluralityof ultraviolet radiation sources, where the radiation sources caninclude a UV-C source (e.g., operating in a range of 220 nanometers to280 nanometers), a UV-B source (e.g., operating in a range of 280nanometers to 315 nanometers), a UV-A source (e.g., operating in a rangeof 315 nanometers to 400 nanometers), and/or a visible source (i.e.,operating in a range of 400 nanometers to 480 nanometers). In anembodiment, at least one of the ultraviolet radiation sources operate ina pulsed mode. In an embodiment, a UV-A source can operate for anextended duration of time, in the range of tens of minutes to a fewhours, while a UV-C source can operate for shorter periods of time, inthe range of a few to a few tens of minutes. In an embodiment, UV-A andUV-C sources alternate operation.

As shown in the intensity plot 400, a device can irradiate differentdomains 402A-D of a surface with different peak intensities 402A-D,depending on the target radiation required. For example, domains 402Aand 402B show peak intensities 404A, 404B of UV-C sources, while domain402C shows a peak intensity 404C for a UV-A source, and domain 402Dshows a peak intensity 404D for a UV-B source.

In an embodiment, the domains 402A-D can comprise periodic regions. Inanother embodiment, the domains 402A-D can be dynamically illuminatedwhere the intensity varies over time. For example, an illustrativedevice 70, as shown in FIG. 9A, can vary intensity according to anembodiment. The device 70 is similar to the device 50B shown in FIG. 5B.However, in an embodiment, at least one of the set of ultravioletradiation sources 52A, 52B (e.g., the ultraviolet radiation source 52B)can oscillate 72 in order to vary the angular distribution of radiation58 and vary the intensity. In a more specific embodiment, at least oneof the set of ultraviolet radiation sources 52A, 52B can move or beangularly rotated. In an embodiment, at least one of the set ofultraviolet radiation sources 52A, 52B can operate in the UV-A range,while at least one of the set of ultraviolet radiation sources 52A, 52Bcan operate in the UV-C range.

Turning now to FIG. 9B, an illustrative system 500 according to anembodiment is shown. The system 500 can include a plurality ofultraviolet radiation sources 502A-D and a diffusive layer 504. In anembodiment, each of the ultraviolet radiation sources 502A-D can have acharacteristic wavelength (e.g., peak emission wavelength) that differsfrom the characteristic wavelength of one or more of the otherultraviolet radiation sources 502A-D. The diffusive layer 504 caninclude any combination of features of diffusive layers describedherein, such as one of the diffusive layers 10, 20, 30, 40 discussed inFIGS. 1-4. In an embodiment, the system 500 can include at least onesensor 506 that is used to measure fluorescent radiation from a surface508 being irradiated by the ultraviolet radiation 510. The system 500can include a control system to receive the fluorescent radiation datain order to adjust the wavelength, intensity, and/or location of theradiation emitted by one or more of the ultraviolet radiation sources502A-D over the surface 508 in order to adjust the resulting radiation510 irradiating the surface 508.

Turning now to FIG. 10, an illustrative system 600 according to anembodiment is shown. To this extent, the system 600 includes a controlsystem 611, shown implemented as a computer system 620, that can performa process described herein in order to operate a device 700 including aset of ultraviolet radiation sources 702 to emit ultraviolet radiationtowards a surface 708 and a set of sensors 704 to measure fluorescentradiation from the surface 708. In particular, the computer system 620is shown including an ultraviolet radiation program 630, which makes thecomputer system 620 operable to control and just ultraviolet radiationfrom the set of ultraviolet radiation sources 702 in the device 700 byperforming a process described herein. In an embodiment, the computersystem 620 can further receive and process data regarding fluorescentradiation at the surface 708 received by the set of sensors 704.

The computer system 620 is shown including a processing component 622(e.g., one or more processors), a storage component 624 (e.g., a storagehierarchy), an input/output (I/O) component 626 (e.g., one or more I/Ointerfaces and/or devices), and a communications pathway 628. Ingeneral, the processing component 622 executes program code, such as theultraviolet radiation program 630, which is at least partially fixed instorage component 624. While executing program code, the processingcomponent 622 can process data, which can result in reading and/orwriting transformed data, such as fluorescent data 634, from/to thestorage component 624 and/or the I/O component 626 for furtherprocessing. The pathway 628 provides a communications link between eachof the components in the computer system 620.

The I/O component 626 can comprise one or more human I/O devices, whichenable a human user 618 to interact with the computer system 620 and/orone or more communications devices to enable a system user 618 tocommunicate with the computer system 620 using any type ofcommunications link. To this extent, the ultraviolet radiation program630 can manage a set of interfaces (e.g., graphical user interface(s),application program interface, and/or the like) that enable human and/orsystem users 618 to interact with the ultraviolet radiation program 630and the fluorescent data 634. Furthermore, the ultraviolet radiationprogram 630 can manage (e.g., store, retrieve, create, manipulate,organize, present, etc.) the data, such as fluorescent data 634, usingany solution.

The I/O component 624 also can comprise one or more I/O interfacesand/or devices, which enables the computer system 620 to operate and/orreceive data from the device 700. In an embodiment, the I/O component626 and device 700 are configured to enable the computer system 620 toselectively operate each of the set of ultraviolet radiation sources 702individually. Alternatively, the I/O component 624 and device 700 can beconfigured to enable the computer system 620 to selectively operatesub-groups of the set of ultraviolet radiation sources 702 individually.In the latter case, a sub-group can be defined as a group of ultravioletradiation sources 702 configured to generate light having substantiallythe same peak wavelength. Similarly, the I/O component and device 700can be configured to enable the computer system 620 to selectivelyoperate set of sensors 704 individually or a sub-groups as describedherein.

In any event, the computer system 620 can comprise one or more generalpurpose computing articles of manufacture (e.g., computing devices)capable of executing program code, such as the ultraviolet radiationprogram 630, installed thereon. As used herein, it is understood that“program code” means any collection of instructions, in any language,code or notation, that cause a computing device having an informationprocessing capability to perform a particular action either directly orafter any combination of the following: (a) conversion to anotherlanguage, code or notation; (b) reproduction in a different materialform; and/or (c) decompression. To this extent, the ultravioletradiation program 630 can be embodied as any combination of systemsoftware and/or application software.

Furthermore, the ultraviolet radiation program 630 can be implementedusing a set of modules 632. In this case, a module 632 can enable thecomputer system 620 to perform a set of tasks used by the ultravioletradiation program 630, and can be separately developed and/orimplemented apart from other portions of the ultraviolet radiationprogram 630. As used herein, the term “component” means anyconfiguration of hardware, with or without software, which implementsthe functionality described in conjunction therewith using any solution,while the term “module” means program code that enables a computersystem 620 to implement the actions described in conjunction therewithusing any solution. When fixed in a storage component 624 of a computersystem 620 that includes a processing component 622, a module is asubstantial portion of a component that implements the actions.Regardless, it is understood that two or more components, modules,and/or systems may share some/all of their respective hardware and/orsoftware. Furthermore, it is understood that some of the functionalitydiscussed herein may not be implemented or additional functionality maybe included as part of the computer system 620.

When the computer system 620 comprises multiple computing devices, eachcomputing device can have only a portion of the ultraviolet radiationprogram 630 fixed thereon (e.g., one or more modules 632). However, itis understood that the computer system 620 and the ultraviolet radiationprogram 630 are only representative of various possible equivalentcomputer systems that may perform a process described herein. To thisextent, in other embodiments, the functionality provided by the computersystem 620 and the ultraviolet radiation program 630 can be at leastpartially implemented by one or more computing devices that include anycombination of general and/or specific purpose hardware with or withoutprogram code. In each embodiment, the hardware and program code, ifincluded, can be created using standard engineering and programmingtechniques, respectively.

Regardless, when the computer system 620 includes multiple computingdevices, the computing devices can communicate over any type ofcommunications link. Furthermore, while performing a process describedherein, the computer system 20 can communicate with one or more othercomputer systems using any type of communications link. In either case,the communications link can comprise any combination of various types ofoptical fiber, wired, and/or wireless links; comprise any combination ofone or more types of networks; and/or utilize any combination of varioustypes of transmission techniques and protocols.

As discussed herein, the control system 611 is configured to operatecomponents of the device 700 to generate ultraviolet radiation directedtowards a surface 708 and detect fluorescent radiation emitted from thesurface 708. The ultraviolet radiation sources 702 in the device 700 cancomprise high intensity, wide coverage sources that are capable ofcontinuous operation in an efficient manner over a large stretch oftime. In an embodiment, the device 700 can include UV-A and/or UV-Bsources capable of operating continuously for a duration of severaldays.

It is understood that both UV-C and UV-A sources are capable ofproducing a distributed intensity over an area at a certain distancefrom the UV sources where distances can range from a few centimeters toseveral meters. As used herein, irradiation of a location defines aregion of the surface that is impinged by radiation, wherein theintensity of radiation deposited at the boundary of the region is atmost 10% of the intensity of light deposited at the center of theregion. It is understood that the position of irradiated locations canbe adjusted to result in separate locations over the surface, whereinseparate means that the intensity of radiation between the locations isno larger than 10% of the intensity in the center of the locations. Inaddition, these locations of irradiation can be designed to haverelatively uniform radiation, with radiation intensity varying throughthe location of no more than several times between any two points withinthe location.

The UV-C and UV-A and/or UV-B radiation sources can comprise anycombination of one or more ultraviolet radiation emitters. Examples ofan ultraviolet radiation emitter include, but are not limited to, highintensity ultraviolet lamps (e.g., high intensity mercury lamps),discharge lamps, ultraviolet LEDs, super luminescent LEDs, laser diodes,and/or the like. In an embodiment, the set of ultraviolet radiationsources 702 can include a set of light emitting diodes (LEDs)manufactured with one or more layers of materials selected from thegroup-III nitride material system (e.g., Al_(x)In_(y)Ga_(1-x-y)N, where0≤x, y≤1, and x+y≤1 and/or alloys thereof). Additionally, the set ofultraviolet radiation sources 702 can comprise one or more additionalcomponents (e.g., a wave guiding structure, a component for relocatingand/or redirecting ultraviolet radiation emitter(s), etc.) to directand/or deliver the emitted radiation to a particular location/area, in aparticular direction, in a particular pattern, and/or the like.Illustrative wave guiding structures include, but are not limited to, awave guide, a plurality of ultraviolet fibers, each of which terminatesat an opening, a diffuser, and/or the like.

In an embodiment, each ultraviolet radiation source in the set ofultraviolet radiation sources 702 can operate at a different peakwavelength (A). In one embodiment, each of the ultraviolet radiationsources in the set of ultraviolet radiation sources 702 can irradiate adifferent location of the surface 708. In one embodiment, theultraviolet radiation sources 702 can irradiate each location withrelatively uniform radiation. In another embodiment, more than oneultraviolet radiation source 702 can be used to irradiate a singlelocation on the surface, with each irradiating the common location at adifferent intensity of radiation.

In an embodiment, at least one of the ultraviolet radiation sources inthe set of ultraviolet radiation sources 702 operates in the lower UV-Ato upper UV-C range. The at least one ultraviolet radiation source canbe configured to irradiate radiation at a specific wavelength selectedfrom a range extending from 250 nm to 360 nm. In general, for adequateoptimization of the irradiation that is provided by the set ultravioletradiation sources 702, the wavelength range can be selected to besignificantly narrower, depending on the type of microorganisms beingsterilized at the surface 708. For instance, the wavelength range canextend from 270 nm to 320 nm, and in some cases, depending on theoptimization target, the range can extend from 280 nm to 300 nm, or from260 nm to 280 nm. In one embodiment, the set of ultraviolet radiationsources 702 can have a peak wavelength that ranges from 270 nm to 300nm. In another embodiment, the set of ultraviolet radiation sources 702can have a peak wavelength of 295 nm with a full width half maximum of10 nm.

In order to facilitate the efficiency of irradiation performed by theUV-C radiation sources, a set of reflective optical elements can be usedto focus the ultraviolet radiation to locations on the surface 708. Inone embodiment, each optical element can be configured to focusultraviolet radiation emitted from one of the ultraviolet radiationsources 702 to a respective location on the surface 708. Examples ofoptical elements that can be used in conjunction with the ultravioletradiation sources include, but are not limited to, a lens and/or a setof lenses.

In an embodiment, the computer system 620 can also control theirradiation of the surface 708 by the set of ultraviolet radiationsources 702 to a plurality of predetermined optimal irradiation settingsspecified for various environmental conditions in which the surface 708is located. In addition, the computer system 620 can adjust theirradiation settings of the set of ultraviolet radiation sources 702 asa function of measurements obtained by the set of sensors 704. Althoughthe computer system 620 is shown to include fluorescent data 634, thecomputer system 620 can include other types of data. In an embodiment,the set of sensors 704 can include other sensors, in addition to afluorescent sensor. For example, the set of sensors 704 can includeenvironmental condition sensors such as a temperature sensor, a humiditysensor, a gas sensor, and/or the like. As such, the data received by thecomputer system 620 can include temperature data, humidity data, gaslevel data, and/or the like. In an embodiment, the data can also includedata associated with the radiation by the set of ultraviolet radiationsources 702, such as the intensity, dosage, duration, wavelength, typeof radiation emitted from the set of ultraviolet radiation sources 702,time duration of irradiation, and/or the like.

In one embodiment, the computer system 620 can also include a wirelesstransmitter and receiver that is configured to communicate with a remotelocation via Wi-Fi, BLUETOOTH, and/or the like. As used herein, a remotelocation is a location that is apart from the system 600. For example, aremote computer can be used to transmit operational instructions to thewireless transmitter and receiver. The operational instructions can beused to program functions performed and managed by the computer system620. In another embodiment, the wireless transmitter and receiver cantransmit data calculations (e.g., changes), data from the sensors to theremote computer, to facilitate further use of the light exposure controlsystem with the surface 708.

In one embodiment, the computer system 620 can include an inputcomponent and an output component to allow the user 618 to interact withthe computer system 620 and to receive information regarding the surface708 and the operating of the set of ultraviolet radiation sources 702.In one embodiment, the input component can permit a user 618 to adjustat least one of the plurality of operating parameters for the set ofultraviolet radiation sources 702. This can include making adjustmentsduring the operation of different radiation sources 702 and/or prior toinitiating a treatment. In one embodiment, the input component caninclude a set of buttons and/or a touch screen to enable a user 618 tospecify various input selections regarding the operating parameters. Inone embodiment, the output component can include a visual display forproviding status information of the surface 708, status information ofthe environment surrounding the surface 708, a simple visual indicatorthat displays whether irradiation is underway (e.g., an illuminatedlight), or if the irradiation is over (e.g., absence of an illuminatedlight).

Turning now to FIGS. 11A and 11B, illustrative plots of operation of adevice as a function of time according to an embodiment is shown. Inparticular, the system can be configured to irradiate surfaces requiringdisinfection with radiation capable of eliciting fluorescent lightresponse from the material located over a surface, wherein the initialirradiation is conducted with the purpose of determining contaminationof the surface based on the amplitude of fluorescent signal sensed by afluorescent sensor. The system can also determine whether to activateUV-C ultraviolet radiation sources or UV-A and/or UV-B radiationsources, depending on the level of contamination and the target leveldesignated by the system. As shown in the FIG. 11A, the system mayirradiate a surface with UV-A and/or UV-B radiation for prolonged periodof time while monitoring the growth of microbes over a surface (e.g.,radiation curve 800). Microbial activity is shown in FIG. 11B as curve802. As can be seen, if microbial activity starts growing rapidly andexceeds a system target threshold 804, UV-C radiation (radiation curve810) is activated to bring microbial activity within appropriate limits.Under such scenario, UV-A and/or UV-B radiation is used to maintainmicrobial activity to within limits over extended periods of time, whileUV-C radiation is designed to rapidly suppress microbial activity.

The ultraviolet irradiation system can further include surfacescomprising photocatalyst. In an embodiment, the photocatalyst can beirradiated by an ultraviolet wavelength in the presence of water vaporto result in formation of hydroxyl group radicals and reactive oxygenspecies (ROS) that can effectively interact and disrupt proliferation ofmicroorganisms. In an embodiment, the ultraviolet wavelength can be inthe range of 360-380 nm. In an embodiment, the ultraviolet wavelengthcan be adjusted to be optimal for ROS and hydroxyl group radicalsformation for each type of photocatalyst present. In an embodiment, thephotocatalyst can comprise known photocatalysts in the art, such asmetal oxides. For example, the photocatalyst can comprise titanium oxide(TiO₂), copper, silver, copper/silver particles, and/or the like. Thephotocatalyst surfaces have to be positioned to be in proximity andirradiated by ultraviolet light, and in close proximity to the surfaceto ensure that created ROS and hydroxyl radicals react mostly on thesurface with microorganisms. In an embodiment, the position ofphotocatalyst has to be that at least 10% of resulting ROS and hydroxylradicals reach the surface.

The system can comprise UV reflective and/or UV diffusive surfacesdesigned to further recycle ultraviolet radiation. In an embodiment,such surfaces can be combined with partially UV transparent surfacesdesigned for further reflection, recycling and light guiding UVradiation. In an embodiment, such surfaces can comprise UV partiallytransparent material such as silicone, fluoropolymers, Al₂O₃, sapphire,SiO₂, CaF₂, MgF₂ and/or the like.

It is understood that in any of the embodiments discussed herein, thediffusive layer can be part of a sterilization system. The sterilizationsystem can include a feedback control system used to measure thefluorescence of the set of items being disinfected. The feedback controlsystem can change the UV radiation intensity, distribution, and/or thelike, depending on the status of the set of items being disinfected.However, it is understood that the diffusive layer can be used invarious other applications. For example, the diffusive layer can beimplemented as part of a system for performing ultraviolet curing.Additionally, the diffusive layer can be utilized in a horticultureultraviolet system. In these applications, inclusion of the diffusivelayer can help prevent a local overdose for the corresponding material,which can destroy or substantially damage the material.

The foregoing description of various aspects of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and obviously, many modifications and variations arepossible. Such modifications and variations that may be apparent to anindividual in the art are included within the scope of the invention asdefined by the accompanying claims.

What is claimed is:
 1. A device, comprising: a set of radiation sourcesconfigured to emit radiation; and a diffusive layer located adjacent tothe set of radiation sources, wherein the diffusive layer includes aplurality of reflective regions formed of a reflective material, and aplurality of at least partially transparent regions, wherein theplurality of at least partially transparent regions are at least 30%transmissive.
 2. The device of claim 1, wherein at least one radiationsource in the set of radiation sources operates in a UV-A range.
 3. Thedevice of claim 1, wherein at least one radiation source in the set ofradiation sources operates in a UV-C range.
 4. The device of claim 1,wherein a characteristic size of the plurality of diffusive elements iscomparable to or larger than the peak wavelength of the emittedradiation.
 5. The device of claim 1, wherein the plurality of diffusiveelements form a set of clusters of diffusive elements, and wherein acharacteristic size of each cluster is at most 5% of the characteristicsize of the plurality of diffusive elements.
 6. The device of claim 1,further comprising a visible light source located adjacent to the set ofdiffusive layers.
 7. The device of claim 1, wherein the at least onepartially transparent region includes a second plurality of diffusiveelements.
 8. The device of claim 1, wherein the at least one partiallytransparent region includes a plurality of transparent elements, aplurality of partially reflective, partially transparent domains, and aplurality of domains with variable reflective properties.
 9. The deviceof claim 1, wherein the at least one partially transparent regionincludes a plurality of particles that fluoresce when exposed toultraviolet radiation.
 10. A device, comprising: a set of radiationsources configured to emit radiation; and a diffusive layer locatedadjacent to the set of radiation sources, wherein the diffusive layerincludes a plurality of reflective regions formed of a reflectivematerial, and a plurality of at least partially transparent regions,wherein at least one of partially transparent regions is formed of afluoropolymer composite, and wherein the plurality of at least partiallytransparent regions are at least 30% transmissive.
 11. The device ofclaim 10, wherein at least one radiation source in the set of radiationsources operates in a UV-A range and at least one radiation source inthe set of radiation sources operates in a UV-C range.
 12. The device ofclaim 10, wherein a characteristic size of the plurality of diffusiveelements is comparable to or larger than the peak wavelength of theemitted radiation.
 13. The device of claim 10, wherein the plurality ofdiffusive elements form a set of clusters of diffusive elements, andwherein a characteristic size of each cluster is at most 5% of thecharacteristic size of the plurality of diffusive elements.
 14. Thedevice of claim 10, further comprising a visible light source locatedadjacent to the set of diffusive layers.
 15. The device of claim 10,wherein the at least one partially transparent region formed of thefluoropolymer composite material includes a second plurality ofdiffusive elements.
 16. The device of claim 10, wherein the at least onepartially transparent region formed of the fluoropolymer compositematerial includes a plurality of transparent elements, a plurality ofpartially reflective, partially transparent domains, and a plurality ofdomains with variable reflective properties.
 17. The device of claim 10,wherein the at least one partially transparent region formed of thefluoropolymer composite material includes a plurality of particles thatfluoresce when exposed to radiation.
 18. An enclosure, comprising: aplurality of radiation sources configured to emit radiation; a pluralityof mirror elements, wherein each radiation source is located above amirror element; and a diffusive layer located on a side of the enclosureopposite of the plurality of radiation sources, wherein the diffusivelayer includes a plurality of reflective regions formed of a reflectivematerial, and a plurality of at least partially transparent regions,wherein at least one of partially transparent regions is formed of afluoropolymer composite, and wherein the plurality of at least partiallytransparent regions are at least 30% transmissive.
 19. The enclosure ofclaim 18, wherein a characteristic size of the plurality of diffusiveelements is comparable to or larger than the peak wavelength of theemitted radiation.
 20. The enclosure of claim 18, wherein the at leastone partially transparent film includes a plurality of transparentelements, a plurality of partially reflective, partially transparentdomains, and a plurality of domains with variable reflective properties.